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Poster Display session (Friday) (ID 65)
- Event: ELCC 2018
- Type: Poster Display session
- Presentations: 1
- Coordinates: 4/13/2018, 12:30 - 13:00, Hall 1
5P - Heterogeneity of PD-L1 expression in primary tumors and paired lymph node metastases of non-small cell lung cancer (ID 501)
12:30 - 13:00 | Author(s): S. Horiuchi
Programmed cell death ligand 1 (PD-L1) expression by immunohistochemistry (IHC) is an important predictive factor for patients with metastatic non-small cell lung cancer (NSCLC). Although PD-L1 IHC 22C3 pharmDx (Dako)® is the first FDA-approved companion diagnostic test for PD-L1 testing in NSCLC, it remains controversial which specimen is preferred from primary tumor or metastatic tissue.
We analyzed formalin-fixed paraffin-embedded tissues of 24 paired primary tumor and metastatic lymph node (LN) from patients with pathological N1 or N2 NSCLC. All of them underwent surgical lung resection and LN dissection (or sampling) at Saitama Cardiovascular and Respiratory Center, and none of them received any chemotherapy or radiotherapy before surgery. According to PD-L1 IHC 22C3 pharmDx interpretation manual, all specimens were stained by using EnVision FLEX visualization system on Autostainer Link 48 in laboratory of LSI Medience Corporation in Japan. Next, we scored and divided each sample into three levels based on a Tumor Proportion Score (TPS); 1) Group 1 (TPS: <1%), 2) Group 2 (TPS: 1–49%) and 3) Group 3 (TPS: >=50%).
All patients were Asian (Japanese) with average age 67.3 years old (49–83). There were 8 females (33.3%), 8 never smoker (33.3%), 19 adenocarcinomas (79.2%) including 7 EGFR mutation and 1 ALK positive tumor. Number of Group 1, 2 and 3 were 5 (20.9%), 15 (62.5%), 4 (16.7%) in primary tumor, while that were 11 (45.9%), 9 (37.5%), 4 (16.7%) in metastatic LN, respectively. No primary tumor in Group 3 paired metastatic LN showing high PD-L1 expression.
We found apparent discrepancy of TPS between primary tumor and metastatic LN of NSCLC, and there are concerns that will cause serious problem when we decide chemotherapeutic agents. It is future subject to explore which site should be biopsied for PD-L1 IHC.
Clinical trial identification:
Legal entity responsible for the study:
Saitama Cardiovascular and Respiratory Center Research Grant, Eiken Chemical Co., Ltd
Y. Saito: This work was supported by the Saitama Cardiovascular and Respiratory Center Research Grant (Grant No. TE17, for Yuichi Saito) and Eiken Chemical Co., Ltd. These funding bodies had no rule in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript. All other authors have declared no conflicts of interest.
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